Fig. 3From: Environmental spreading of clinically relevant carbapenem-resistant gram-negative bacilli: the occurrence of blaKPC-or-NDM strains relates to local hospital activitiesFrequency analysis of blaKPC-or-NDM isolates recovered from STPs (raw sewage). Frequencies were distributed among categorized groups of STPs considering regional attendance profiles: A volume (L/s) of inflow sewage in the STPs; B sewer connections serviced by STPs; C the total number of hospitals D occurrence of tertiary-level district hospitals within 3 Km from the STPs; E the number of hospitalizations in areas serviced by STPs; F built area (m2) for pig/poultry farming within 3 Km from the STPs; and G participation of agricultural employment in areas serviced by STPs. Levels of significance for the distribution analysis (Fisher’s Exact Test) and for the linear relationship analysis (Cochran-Mantel-Haenszel test) are displayed in each graphBack to article page